Do not try to force accessibility on Parent.getChildren via reflect…

…ion,

to avoid `InaccessibleObjectException` at runtime.

Fixes edvin/tornadofx#1217, edvin/tornadofx#1270, edvin/tornadofx#1276.

See also: edvin/tornadofx@4b4f39f

src/main/java/tornadofx/FX.kt

@@ -694,14 +694,11 @@ fun EventTarget.getChildList(): MutableList<Node>? = when (this) {
 }
 
 @Suppress("UNCHECKED_CAST", "PLATFORM_CLASS_MAPPED_TO_KOTLIN")
-private fun Parent.getChildrenReflectively(): MutableList<Node>? {
-    val getter = this.javaClass.findMethodByName("getChildren")
-    if (getter != null && java.util.List::class.java.isAssignableFrom(getter.returnType)) {
-        getter.isAccessible = true
-        return getter.invoke(this) as MutableList<Node>
-    }
-    return null
-}
+private fun Parent.getChildrenReflectively(): MutableList<Node>? = this.javaClass
+    .findMethodByName("getChildren")
+    ?.takeIf { java.util.List::class.java.isAssignableFrom(it.returnType) }
+    ?.takeIf { getter -> getter.canAccess(this) || getter.trySetAccessible() }
+    ?.let { getter -> getter.invoke(this) as MutableList<Node> }
 
 var Window.aboutToBeShown: Boolean
     get() = properties["tornadofx.aboutToBeShown"] == true